Electromagnetically activated valves, such as solenoid or electropneumatic changeover valves, are used in changeover, disconnection or vent devices, and are employed, for example, in activated-charcoal filter systems of internal combustion engines of motor vehicles or in combination with pneumatic actuators.
As known, an electromagnetically actuated changeover valve comprises a coil, an armature and a restoring spring. In the energized state, the armature is attracted by the magnetic force of the coil against the force of the restoring spring, thus opening or closing a valve inlet or outlet of the changeover valve. Such an electromagnetically actuated changeover valve is disclosed, for example, in German Patent Application DE 19733577 A.1.
A disadvantage of this type of valve, however, is that an autonomous functional check is not provided, of whether the armature actually opens or closes the inlet or outlet when it is in the energized state.